The effect of dietary omega-3 fatty acids (fish oil) on azoxymethanol-induced focal areas of dysplasia and colon tumor incidence

Article Abstract:

There has been much discussion of the apparent ability of fish oils to reduce the likelihood of coronary heart disease. These oils, which contain fatty acids unsaturated in the omega-3 position of their molecular structure, are thought to exert their influence by inhibiting prostaglandin synthesis. Since inhibitors of prostaglandin synthesis are also thought to prevent or reduce the formation of chemically-induced tumors, the effects of fish oils on the development of tumors in experimental animals was investigated. Tumors were induced in mice with the carcinogenic agent azoxymethanol. The mice were divided into groups that were given diets with differing amounts of fish oil mixed with corn oil; diets ranged from high corn oil (containing omega-6 fatty acids), to low corn oil and high fish oil mixtures (containing greater amounts of the presumably desirable omega-3 fatty acids). The diets were begun two weeks prior to the injections of azoxymethanol, which were given weekly for six weeks. After this time, the intestine tissue of the animals was examined for precancerous changes. The animals fed the diet highest in fish oils had intestines that most closely resembled the intestines of the control animals (who were injected only with saline instead of carcinogen). The greatest levels of cell proliferation were observed in the animals fed the highest levels of corn oil and the lowest levels of fish oil. The diet with equal quantities of fish oil and corn oil, 10.2 percent of each, yielded the lowest number of actual tumors in the experimental mice. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Causes of, Carcinogenesis, Omega-3 fatty acids, Omega 3 fatty acids, Fish oils, Omega-6 fatty acids

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Increasing incidence of cecal and sigmoid carcinoma: data from the Connecticut Tumor Registry

Article Abstract:

Although rectal cancer and cancers of different regions of the colon are often classed together as colorectal cancer, it is important for epidemiologists to consider them separately to discern changes and trends in cancer frequency. Using the Connecticut Tumor Registry, which is the oldest cancer registry in the US, researchers have explored changes in the incidence of rectal cancer, cancer of the sigmoid colon, and cancer of the cecum during the period between 1935 to 1985. During this time, the age-adjusted incidence of rectal cancer has changed little (22.8 cases per 100,000 per year for men, and 13.9 cases per 100,000 per year for women). This stability of incidence is not observed with colon cancer, which is on the rise. Among men, the age-adjusted incidence of cecal carcinoma has risen from 3.6 to 16.7 cases per 100,000 per year over the 50-year study. The age-adjusted incidence of sigmoid colon cancer has risen from 8.8 to 18.7 per 100,000 per year over the same period. A similar rising trend is observed among women, who in 1935 had rates of 4.9 and 7.7 cases per 100,000 per year for cecal and sigmoid colon cancer, respectively. By 1985, these rates had risen to 14.2 and 12.8 per 100,000 per year. The available evidence suggests that this trend is not leveling off, and the incidence of colon cancer continues to rise at an apparently constant rate. (Consumer Summary produced by Reliance Medical Information, Inc.)

Statistics, Cancer patients

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